Electrical feedthroughs have been known for some time in the implantology of electrical implants. They are used for the purpose of leading electrical contacts outward from the interior of the implant insulated from the implant housing, without the tightness of the implant being endangered.
In a simple construction, a feedthrough includes an electrically conductive flange, which includes the same material as the implant housing (typically titanium), and a terminal pin, with the aid of which the electrical contact is produced between the implant interior and its surroundings. The terminal pin is led inside an insulator, which preferably consists of a ceramic or solely of a glass solder, which is in turn connected on its outer side to the flange. Such electrical feedthroughs are typically implemented as round and usually lead one, or normally also multiple, terminal pin(s) (also referred to as multiple feedthroughs). However, single feedthroughs which have a common flange are also suitable.
Problems may occur if the terminal pins are joined, on the side lying in the implant interior, to an electrical circuit using thermal methods, for example. In this case, heat damage may occur on the electrical circuit located in the implant, for example, if the terminal pin can only be joined using brazing or welding methods. Therefore, the terminal pin is to include a material which can be soft soldered easily, i.e., can also be wetted easily using soft solder, so that the circuit is not damaged during the joining, for example, using reflow soldering. For example, nickel or nickel alloys are known as materials which can be soft soldered. Difficulties arise in the described terminal pins including the described materials which can be soft soldered upon connection of the insulator, because detachment of the insulator can occur and/or the wetting capability with solder is poor. A terminal pin made of niobium (Nb), Pt, Pt/Ir, FeNi, FeNiCo, FeCr, Ta, Mo, W, Cr, FeCr, V, Ti, and further metals or their alloys, for example, may advantageously be hermetically connected to the insulator as well, but niobium can only be welded and is therefore not usable for being electrically connected to an electrical circuit.
The present invention is directed at overcoming one or more of the above-mentioned problems.